Explain `sp^(2)` hybridisation in `BF_(3)`.

Explanation

`sp^(2)` Hybridisation :
Consider boron trifluoride molecule . The valence shell electronic configuration of boron atom is `1s^(2) 2s^(2) 2p^(1)`.

In the ground state boron has only one unpaired electron in the valence shell. In order to form three covalent bonds with fluorine atoms, three unpaired electrons are required . To achieve this, one of the `2p_(y)` orbital in the excited state .
In boron, one s orbital and two p orbitals `(p_(x)"and "p_(y))` in the valence shell hybridses, to generate three equivalent `sp^(2)` orbitals as shown in the Figure. These three orbitals lie in the same xy plane and the angle between any two orbitals is equal to `120^(@)`

Overlap with 2pz orbitals of fluorine :
The three `sp^(2)` hybridised orbitals of boron now overlap with the `2p_(z)` orbitals of fluorine (3 atoms).
This overlap takes place along the axis as shown below.